Westermark's sign of pulmonary embolism--well known but frequently overlooked.

Pulmonary embolism (PE) is frequently a difficult diagnosis because of non-specific symptoms that can lead to misdiagnosis 1 . We report a patient with PE successfully diagnosed and treated, whose CXR showed Westermark’s sign of pulmonary embolism. Westermark’s sign is distal oligaemia in the affected area of the lung due to a reduction in size of vessels distal to a PE 2 . It has a low sensitivity (14%) and high specificity (92%) for the diagnosis of pulmonary embolism 3 . Its high specificity for PE makes it a sign well worth being aware of and in this case described its early recognition may led to early treatment and to prevention of cardiovascular insult.